Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the agent knows this is a safe, closed-domain computation. The description adds genuine value beyond that: it discloses that the amounts are approximate and that the returned notes carry conditions which can alter them, i.e. outputs are estimates with caveats rather than authoritative figures.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tightly packed sentences with no filler: the first front-loads the scope and cost components, the second front-loads the caveat about accuracy. Nothing is repeated from the schema or title.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only, 4-parameter estimator with no output schema and no nested objects, the description covers scope, the conditional tax branches and the reliability caveat. The only minor gap is that it does not hint at the shape of the returned breakdown, though the mention of notes partially covers that.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is only 50% (obra_nueva and precio_vivienda have no schema description). The description compensates by tying comunidad and itp_joven together (regional ITP with youth rate) and by explaining what obra_nueva actually switches (IVA + AJD, or IGIC + AJD in Canarias), giving real semantic meaning to the two undocumented booleans.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description gives a specific resource ('Desglose de impuestos y gastos de comprar una vivienda') and enumerates exactly what is covered (ITP/IVA/AJD/IGIC, notaría, registro, tasación, gestoría), so the agent can immediately tell this is a transaction-cost estimator rather than a payment or capacity calculator. It never explicitly contrasts itself with siblings like mortgage_calcular_cuota or mortgage_calcular_capacidad, which caps it at 4 under the rubric.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explains which tax regime applies under which condition (ITP by region with the youth rate, vs IVA+AJD for obra nueva), but that is calculation logic, not when-to-use guidance. There is no statement of when this tool should be chosen over alternatives, no prerequisites, and no exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.